[ARC5] Crystals in WWII

[Kenneth G. Gordon]

On 15 Mar 2013 at 0:40, Dennis Monticelli wrote:

> I think the "dirt" problem had mostly to do with fine grit left over
> from the grinding process and also quartz molecules left weakly
> attached to the crystal.

Yes. Exactly.

>  Neither would appear to the eye after a
> routine wash.

I know that when grinding crystals to frequency by hand, a good method of 
cleaning them is with a toothbrush and plenty of scrubbing. But, even doing 
that will not get the crystals completely clean.

To REALLY get them clean requires etching with HF.

>  The fix was discovered and implemented by Bliley.  They
> were doing an acid etch to take a ground blank a short distance to the
> final freq.  It turned out that the etch also did an outstanding job
> of removing several atomic layers (where the surface damage was) and
> leaving behind a clean nicely ordered crystal lattice.

Yup.

>  There was
> nothing left on the surface to redistribute after manufacture and use,
> hence no "aging."   Bliley didn't want to share the knowledge because
> they wanted to retain an advantage in the market after the war.  The
> govt twisted their arm and the technique was shared, just as all the
> previous crystal technology had been shared earlier in the war to
> create the cottage industry.

Yes, but if the gummint hadn't twisted some arms then and there, many lives 
would have been lost.

BTW, for those who are interested, a product named "Whink", available in 
most supermarkets in the laundry supplies section contains a small amount 
of HF.

It will etch crystals, although very slowly. It does an excellent job of cleaning 
crystals after grinding them by hand.

Ken W7EKB